In the last bond sale, in January, the average yield was 2.920%.


Demand was €2.348 billion, 1.88 times the supply.


"Portugal continues to be able to issue in the long term, at low rates," said Filipe Silva, director of asset management at Banco Carregosa, noting "yet another historic minimum" in yields.


Although the yields are not on the face of it very attractive to investors, he said, there are other countries that are currently offering negative interest rates for 5-year debt, making Portugal's debt of more interest.


"Portugal has never paid such a low interest rate in the market, which is very advantageous for its intention of paying off early the International Monetary Fund loan," he noted.


The government this week confirmed that it was seeking permission to repay early €14 billion in IMF loans contracted as part of Portugal's €78-billion euro-zone bailout, over the next two and a half years.